The bitter cold that gripped the snow-covered northern tier from Cleveland to Boston on Friday shows no sign of easing, as another arctic blast roaring out of Canada threatens to drive weekend temperatures to all-time record lows.

The National Weather Service said "dangerously cold temperatures" will slam the Northern Plains and Upper Midwest through the weekend, driving wind chill temperatures in some areas to below -60 degrees F.

The weather service warned that "wind chills colder than 50 below can cause exposed flesh to freeze in only 5 to 10 minutes."

Minnesota Gov. Mark Dayton announced Friday that all schools in the state would be closed on Monday. All-time record cold temperatures are possible in Minneapolis on Monday, according to the weather service.

The combination of arctic air with the gusty winds is expected to lower wind chill temperatures to the single digits over the Mid-Atlantic while areas of New England can expect wind chill readings into the -10s and -20s, the weather service said.

Before the full force of the Arctic blast roars in, another winter storm will spread snow and ice from the central Plains to the Great Lakes states this weekend. The heaviest snow is forecast to hit St. Louis, Indianapolis, Detroit, Cleveland, and Buffalo, AccuWeather predicts, from late Saturday into early Monday.

The storm will also bring snow and slippery travel to much of the Ohio and Tennessee valleys, AccuWeather meteorologist Courtney Spamer said.

Much of the eastern half of the country is already reeling from Thursday's killer storm that has shut down airports and major roads and forced school closings in much of the Northeast.

At least 13 people died in the storm: Slick roads were blamed for traffic deaths in Michigan, Kentucky, Indiana and Illinois. Authorities said a 71-year-old woman suffering from Alzheimer's disease froze to death after she wandered away from her rural western New York home.

The storm - which brought plummeting temperatures as low as 8 degrees below zero to Burlington, Vt., early Friday with a wind chill of 29 below zero - dumped 23 inches of snow in Boxford, Mass., by early Friday and 18 inches in parts of western New York near Rochester. Ten inches of snow fell in Lakewood, N.J., and up to 7 inches fell in New York City.

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Governors in New York and New Jersey declared states of emergency, urging residents to stay at home.

"This is nothing to be trifled with," New York Gov. Andrew Cuomo said. "People should seriously consider staying in their homes."

Strong winds also forced the shut down of JFK International Airport on Friday morning. Major highways were also closed in New York and Pennsylvania.

By 5 p.m., 3,210 flights were canceled nationwide and 6,896 were delayed, according to FlightStats.com., which tracks flights. Philadelphia had 486 flights canceled, New York's LaGuardia had 454, and Newark had 433, and Boston had 380.

The harsh winter storm was the first test for new New York City Mayor Bill de Blasio, who as public advocate in 2010 criticized his predecessor Mayor Michael Bloomberg for his handling of a large snowstorm.

As soon as snow began falling Thursday night, de Blasio sent hundreds of plows and salt spreaders on the streets.

"If you don't need to go out, please don't go out," de Blasio said at a news conference Thursday evening, urging residents to use mass transit. "Stay off the streets, stay out of your cars."

In suburban Philadelphia, a worker using a backhoe at a salt storage facility was killed when a 100--foot-tall pile of road salt collapsed and crushed him.

In parts of New York State, roads were snow-packed and treacherous Friday morning with few drivers venturing out early in the frigid temperatures and wind-whipped snow, The (Westchester County, N.Y.) Journal-News reports.

"The roads are sloppy everywhere, but the department of public work crews are out there," Tuckahoe Police Sgt. David Banks said.

The New York State Thruway, closed overnight between Albany and Yonkers, reopened to passenger cars at 5 a.m. Friday, but commercial traffic remained banned until 8 a.m. Interstate 84 remained closed to all traffic until 8 a.m.

A 71-year-old woman was found dead in the snow in her back yard in New York's Genesee County on Thursday night.

Carol Magoffin of Byron was found about 100 yards behind her home at about 9:30 p.m., said Chief Deputy Jerome Brewster of the Genesee County Sheriff's Office.

Magoffin, who had been ill, apparently wandered away from the home she shared with her husband, Robert, on Thursday. He had been napping and awoke to find his wife missing, deputies said.

In Delaware, up to 9.4 inches of snow was reported on the ground in parts of the state. A major headache was expected to be drifts caused by northwest winds gusting to 35 mph, The (Wilmington) News-Journal reports.

Wilmington city offices and schools, along with state, and county offices in the area, were closed for the day.

About 100 homeless people found shelter from the storm Thursday night at the Sunday Breakfast Mission in Wilmington, said the Rev. Tom Laymon, president and chief executive officer.

Laymon told the arrivals to "please don't let your friends stay out in this cold." He also urged the public not to ignore homeless people out in the extreme cold.

"Call the police and they'll pick them up and bring them to us," he said. "We don't want anyone dying unnecessarily from the cold."

Not everyone wanted to be indoors. In Ocean City, Md., surfers in wetsuits ignored the -3 degree wind chill and the ocean's 41 degrees to take advantage of waves being whipped up by a stiff wind Friday.

"If there are waves like this, guys are going to go out," said Lee Gerachis, owner of Malibu's Surf Shop. He said one surfer said he was hot in his winter-weight wetsuit, which is warmer and stronger than older versions.